In this paper we propose a novel algorithm that, given a source robot S
and a target robot T, reconfigures S into T. Both
S and T are robots composed of $n$ atoms arranged in
2 × 2 × 2 meta-modules. The reconfiguration
involves a total of O(n) atom operations (expand, contract,
attach, detach) and is performed in O(n) parallel steps. This
improves on previous reconfiguration algorithms [1–3], which require
O(n2) parallel steps. Our algorithm is in place;
that is, the reconfiguration takes place within the union of the bounding
boxes of the source and target robots. We show that the algorithm can also be
implemented in a synchronous, distributed fashion.